Loudspeaker plastic cone body

Abstract

A loudspeaker cone body made of plastic includes a base carrier material and a filler material. The base carrier material is selected to optimize overall flow, weight and stiffness. The filler material may be a nanomaterial that provides for adjustment of process and acoustic related characteristics in the loudspeaker cone body that become relevant when the loudspeaker cone body is operated in a loudspeaker. Acoustic related characteristics that may be adjusted include a stiffness to weight ratio and an acoustic damping of the loudspeaker cone body. A predetermined weight percent of the filler material may be combined with the base carrier material to obtain repeatable desired acoustic related characteristics. The acoustic related characteristics may be adjusted by changing the predetermined weight percent of the filler material.

Description

PRIORITY CLAIM [0001] This application claims the benefit of priority from U.S. Provisional Application No. 60 / 629,907, filed Nov. 22, 2004, which is incorporated by reference.BACKGROUND OF THE INVENTION [0002] 1. Technical Field [0003] This invention relates to loudspeakers, and more particularly, to a loudspeaker plastic cone body. [0004] 2. Related Art [0005] A loudspeaker cone is a well-known part of every mid and low frequency loudspeaker. In addition, it is well known that a desirable loudspeaker cone body is one with sufficient amount of stiffness and minimized weight. This is known as stiffness to weight ratio. A specific modulus, Ys=Ye(Young's Modulus) / specific gravity, is defined as a figure of merit to compare and rank alternate materials and compositions. [0006] Many of today's loudspeaker cone bodies are made of paper. Unfortunately, paper cone bodies may exhibit moisture problems. In addition, manufacturing tolerances of paper cone bodies are undesirably large. [0007] ...

AI Technical Summary

Benefits of technology

[0008] The invention discloses a loudspeaker plastic cone body that is formed to include a base carrier material and a nanofiller. The nanofiller may be combined with the base carrier material in a predetermine weight percent to adjust a number of process and acoustically related characteristics of the loudspeaker cone body. Adjustment of the weight percentage of the nanofiller advantageously allows adjustment of acoustically related characteristics that affect stiffness to weight ratio and damping.

[0009] Due to the properties of both the base carrier material and the nanofiller, a compromise may be maintained between the otherwise conflicting goals of processability, low weight of the cone body, optimized stiffness and optimized acoustical damping. Processablity involves the improved flow characteristics to achieve improved manufacturablity of thin walled cones. Thus, as the weight percentage of the nanofiller in the base carrier material is increased, the stiffness may be increased and acoustical damping may be decreased without substantially increasing the weight of the cone body. The lack of a substantial increase in the weight of the cone body is due to the efficient additive properties of the nanofiller within the base carrier material. A relatively small weight percentage of nanofiller may provide a relatively large percentage change in stiffness, and damping at equivalent stiffness. Thus, a compromising balance may be achieved between the desire to optimize competing characteristics in the plastic cone body.

[0011] The cone body may be formed with a relatively thin sidewall using a molding process, such as injection molding. Thus, the tool used to mold the cone body part may include relatively close tolerances. The combination of the base carrier resin and the nanomaterial may advantageously possess sufficiently low viscosity (adequate shear rates) to fill such relatively close tolerances. The complimentary combination of the base carrier resin and the nanomaterial may provide sufficiently low viscosity over a range of weight percent of the nanomaterial without conflicting with the desired process and acoustical characteristics. Relatively high flow properties and relatively low specific gravity of the base carrier material may not be significantly compromised by the addition of the nanomaterial. In addition, shear thinning properties that may be included in the nanomaterials and the relatively small weight percentage of nanomaterial added to the base carrier material to achieve the desired process and acoustical results may have a favorable effect on the viscosity. Accordingly, satisfactory mold filling capability in thin walled sections may be maintained while still maintaining desirable stiffness to weight ratios and acoustical damping characteristics.

Problems solved by technology

Unfortunately, paper cone bodies may exhibit moisture problems.

In addition, manufacturing tolerances of paper cone bodies are undesirably large.

Although moisture and repeatability may be less of an issue with unfilled polypropylene, such cone bodies still exhibit a relatively low stiffness to weight ratio due to a relatively low modulus of un-reinforced polypropylene.

Thus injection molding of larger cone bodies with thin wall sections is difficult.

Further, such fillers increase material specific gravity so that the weight of a cone design increases as well.

Therefore, to obtain sufficient stiffness characteristics, the weight of cone bodies may become undesirably high for optimal acoustic performance.

The lack of a substantial increase in the weight of the cone body is due to the efficient additive properties of the nanofiller within the base carrier material.

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